The Photon
In Our Time: Science
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Newton's Law of Gravity
Although photons have famously as we know now no mass they're affected by gravity um how do we know this well I thought first question you were going to probably say paradoxically if they've got no mass how can they be affected by gravity. Newton's law is what we learn for massive bodies we now know since Einstein that that is an approximation to a richer description and roughly speaking it's not the masses that are important it's the energy that's important so even a massless photon because it has energy can feel a gravitational force. Frank Eddington: The famous experiment that Eddington did during a total solar eclipse in 1919 or there measured the deflection of the stars in the near line
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